Patch

Our heads are a pent roof design. Efficient and inherently detonation resistant. Running a compression ratio of 11.68 or higher on pump gas without a computer specifically reprogrammed may/will cause detonation. Even light load det. can quickly destroy your new engine. If you retard the distributor enough to kill the light load detonation, your spark will be so retarded at the WOT parts of the map that you will lose more power than the high compression will cause you to gain. The heat produced by the retarded spark can also result in a thermal runaway condition where it is impossible to keep the engine cool.

Mdrigrappa - since you are milling the head, I would weld up the quench pads of the combustion chamber. These are the flat edges on the sides of a four-valve pentroof combustion chamber. The advantage here is threefold. Increasing the quench area of a combustion chamber increases the amount of turbulence in the chamber as the piston comes to TDC on the compression stroke. This creates a more homogeneous mixture of fuel and air throughout the chamber for a more even burn. The additional turbulence also speeds flame propagation. These factors make for more efficient combustion, aiding exhaust emissions, fuel economy and power. In adition, quench area makes the chamber more detonation resistant.

AusS2000

[QUOTE]Originally posted by mdigrappa
[B]If this is true, then i should be able to run a JDM ECU such as a Spoon or BYS with no problems.

ultimate lurker

The gear is definitely not adjustable. You could try and offset woodruff key, but as small as the gear is, it would be difficult to do and do accurately. Just got some more info on the adjustable gears too, looks like the cost will be around $600/set. These things are pretty complex (hint - the factory gears for older DOHC VTEC engines are one piece, the factory gears for the F20C have at least 5 pieces and will have even more when adjustable).

Joe, I'm not sure about welding up quench pads just yet. The factory head has recessed quench pads that appear to be designed to work with the factory domed piston. Obviously you could bring them down somewhat since thinner head gaskets are o.k., but I don't know about welding them flat with the head surface. I'd need to take apart the engine first I guess.

In terms of compression, I'm sure 11.8:1 will work just fine. I mean, even the Porsche 911 is running 11.3:1 with a huge bore and Honda combustion chambers are awesome.

UL

Patch

[QUOTE]Originally posted by ultimate lurker
[B]Joe, I'm not sure about welding up quench pads just yet.

mdigrappa

From what I understand welding the quench pads would have the opposite effect that you are talking about. Also I was wondering if the head is the same part as the JDM. If it is and the pistons are as well then there should be no worries until 12.5 compression (or so) I am thinking of going more compression than I was originaly planning, because I live at 6000 feet and can theoreticaly get away with it. I will probably run 101 octane fuel as well. Any advice is appricated. BTW I love this discussion, you guys are great! I would have not been able to optimize my project without you
THANKS!!
Mark

McHeizer

[QUOTE=,May 28 2001, 07:15 PM] Just got some more info on the adjustable gears too, looks like the cost will be around $600/set.

StealthimageS2k

...ppl really have to stop bringing back ancient threads.....and the adjustable cam gears are offered by toda.

McHeizer

yeah right "ancient" this is about 2.5 months old, so get real!

thx for the answer!
I knew about the Toda gears, thought this would be maybe another company - in the US - offering those.

RedChili

[QUOTE=McHeizer,Aug 13 2008, 10:54 PM]yeah right "ancient"

McHeizer

oops ok - I really didn't realize that sorry!!